Rail for a window covering



FIG. 1 is a bottom perspective view of a rail for a window covering showing our design;

FIG. 2 is a top perspective view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a front elevational view thereof, the rear elevational view being a mirror image thereof; and,

FIG. 6 is a bottom plan view thereof.

The broken lines in FIGS. 1, 2, 4, 5 and 6 depict the boundary of the claim and form no part of the claimed design. 

CLAIM The ornamental design for a rail for a window covering, as shown and described. 